Simplify the following expression: $r = \dfrac{-8n + 5}{2n} \div \dfrac{1}{5}$
Solution: Dividing by a number is the same as multiplying by its inverse. $r = \dfrac{-8n + 5}{2n} \times \dfrac{5}{1}$ When multiplying fractions, we multiply the numerators and the denominators. $r = \dfrac{(-8n + 5) \times 5} {(2n) \times 1}$ $r = \dfrac{-40n + 25}{2n}$